The Saint Bernard runs $150–$310 a month and $2,200–$4,200 in the first year, against the Akita's $110–$240 and $1,700–$3,200.
Food is the visible part — a 160-pound dog eats a great deal, and large-breed puppy food for eighteen months is a serious line on its own. Everything else scales too: parasite treatment, most medications, anaesthesia, joint supplements and boarding are all priced by weight.
The large risks are large in proportion. Bloat surgery, cardiac management, eyelid correction and orthopaedic procedures in a giant dog are all four-figure events, and insurance for giant breeds is priced with that in mind. Check the excess structure as well as the premium.
The one place the Saint Bernard saves you money is exercise equipment and time — 2/5, two moderate walks, timed around temperature.
And the number that frames all of it is the lifespan. Eight to ten years is a short return on that investment, and it is the honest reason many people who love the breed choose something smaller the second time.